Positive integers k such that 2^(k+2) - 1 is divisible by k.

Terms

a(0) =1a(1) =7a(2) =511a(3) =713a(4) =11023a(5) =15553a(6) =43873a(7) =81079a(8) =95263a(9) =323593a(10) =628153a(11) =2275183a(12) =6520633a(13) =6955513a(14) =7947583a(15) =10817233a(16) =12627943a(17) =14223823a(18) =15346303a(19) =19852423a(20) =27923663a(21) =28529473a(22) =29360527a(23) =31019623a(24) =39041863a(25) =41007823a(26) =79015273a(27) =134217727a(28) =143998193a(29) =213444943